Category : C Source Code
Archive   : XMS11.ZIP
Filename : XMS.H

// Microsoft eXtended Memory Specification
// C++ Interface Library Header File
// by Richard Vuduc
// Copyright 1990, Richard Vuduc

#ifndef _XMSMGR
#define _XMSMGR 1

// Types and constants
enum boolean { False, True }; // analogous to Pascal's boolean
const HMASeg = 0xFFFF; // Last physical segment in real-mode
const HMAOff = 0xA; // 16 bytes + HMASeg = The 1 MB boundary

#ifndef NULL
#define NULL 0
#endif

class XMSDriver; // Incomplete declaration
#include "xmshndl.h"

// Extended Memory Block Move structure
struct XMSMoveBlock
{
unsigned long Length; // Length of move block, in bytes
unsigned int SrcHandle; // Source Handle #; 0 = conventional Mem
unsigned long SrcOffset; // Offset of source handle or off,seg
unsigned int DestHandle; // Destination handle
unsigned long DestOffset; // Destination offset
};

// XMSDriver class
// Handles allocation and deallocation of XMS blocks
class XMSDriver
{
static long Avail; // Extended Memory available to application
static long Total; // Total extended memory installed
static boolean Installed; // XMM installed?
boolean InstHMA; // XMM HMA available
char far *HMAPtr; // Pointer into High Memory Area
XMSHandle *CurrHandle, // Linked list - Current handle
*First, // First handle in linked list
*Last; // Last handle in linked list
public:
XMSDriver( void ); // constructor
~XMSDriver( void ); // destructor

// ***************** High Memory Area management functions (1024K-1088K)
boolean ReqHMA( void ); // Allocate HMA
void RelHMA( void ); // Deallocate HMA
void far *GetHMAPtr( void ); // Get a pointer to HMA
boolean A20Enable( void ); // Globally enable A20 line
void A20Disable( void ); // Globally disable A20 line
boolean A20LEnable( void ); // Locally enable the A20 line
void A20LDisable( void ); // Locally disable the A20 line
boolean A20Query( void ); // Query state of A20 line
void far *HMAWrite( unsigned ItemSize, unsigned Index, unsigned Length,
void far *Data ); // Write a block to high memory
// Read from HMA
void far *HMARead( unsigned ItemSize, unsigned Index, unsigned Length,
void far *Data );

// **************** Extended Memory Block Functions... (1088K+)
unsigned EMBAlloc( unsigned size ); // Allocate EMB
void EMBFree( unsigned handle ); // Free EMB
long EMBLock( unsigned handle ); // Lock EMB
boolean EMBUnlock( unsigned handle ); // Unlock EMB
boolean EMBMoveToExt( unsigned dhandle, unsigned doff,
void far *p, long size );
boolean EMBMoveToCon( void far *p, unsigned shandle, unsigned soff,
long size );
boolean EMBExtToExt( unsigned dhandle, unsigned doff,
unsigned shandle, unsigned soff, long size );
boolean EMBRealloc( unsigned handle, unsigned size ); // Realloc block

// **************** Upper Memory Block management routines (640K - 1024K)

// **************** Miscellaneous Management routines
long GetAvail( void ); // Get available Extended Memory
boolean Inst( void ) { return Installed; } // XMS Installed?
boolean HMAInst( void ) { return InstHMA; } // HMA Installed?
long GetTotal( void ) { return Total; }

// **************** XMS Hi-Level Memory Managment Routines
XMSHandle *HndReqPtr( unsigned handle );
void HndRelPtr( unsigned handle );

// Internal functions - private only
private:
void CopyBlock( char far *dest, char far *src, unsigned len );
void XMSChainHandle( unsigned int handle, unsigned int size );
XMSHandle *XMSFindLastHandle( void ) { return (CurrHandle=Last); }
XMSHandle *XMSFindFirstHandle( void ) { return (CurrHandle=First); }
XMSHandle *XMSFindHandle( unsigned handle );
};

#endif
// End XMS.H